ML20209C910
| ML20209C910 | |
| Person / Time | |
|---|---|
| Site: | MIT Nuclear Research Reactor |
| Issue date: | 07/08/1999 |
| From: | MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE |
| To: | |
| Shared Package | |
| ML20209C896 | List: |
| References | |
| NUDOCS 9907120310 | |
| Download: ML20209C910 (10) | |
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Environmental Report Massachusetts Institute of Technology Research Reactor MITR-III O
July 8,1999 l
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'i; Table of Contents 1 General.....................................................................................IT 2 S ite Descripti on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -
3 Environmental Effects of MITR Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1 Thermal Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2 Radiological Impact During Normal Operation.............................. 3 3.2.1 Environmental Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2.2 Personnel Exposure Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2.3 S olid Wastes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 O
V 3.2.4 Li qu i d Wastes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 ,
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t 3.2.5 Radioactive Gas Effluent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 i
-i 3.2.6 Spent Fuel Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. Radiological Impact During Abnormal Operation ........................... 5 Benefits of Facility Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1 4 '
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.5 Con cl u si on s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1 rad i ol ogical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.2 . Radi ological . . . . . . . . . . . . . . . . . _. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 uO
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i 1 General
.This document summarizes the environmental effects that are imposed by operation of the Massachusetts Institute of Technology Research Reactor (MITR-III) that is owned and operated by the Massachusetts Institute of Technology. The requested steady-state power of the MITR-IIIis 6000 kW.
2 Site Description The MITR is situated on the MIT campus which is in tum located within a metropolitan area. This site was selected to promote the exchange of ideas between educators and researchers at both MIT and other local-area universities. A further reason for choosing this site was its proximity to many major medical centers. Such proximity is necessary in order to foster scientific collaboration, to provide the timely delivery of shon- j t
m li'.ed isotopes for medical research, and to permit patient therapy using neutron beams. In I i
w.J view of the urban setting for the MITR,it was decided to employ a full containment. This i building, which is equipped with both underpressure protection and an overpressure relief system,is designed to protect the public from radioactive effluents in the event cf a facility accident. A complete description of the containment building is given in the MITR-III l I'
Safety Analysis Report (SAR) Section 6.5.
The reactor site measures approximately 86 m (280 ft.) in length and 46 m (150 ft.)
in width. Included in this area are the reactor building, an adjoining one-story building that !
houses laboratories and storage areas as well as reactor support equipment such as electrical switchgear, Building NW12, the cooling tower, the ventilation exhaust stack, and a parking lot. Building NW12 contains offices, classrooms, laboratories, and auxiliary equipment associated with the reactor. The reactor building is connected to the one-story building by an air lock. Entry to structures and areas inside the one-story building, the
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reactor containment building, and the area occupied by the cooling tower and ventilation exhaust stack is restricted.
The reactor site is in the midst of a heavily commercialized section of Cambridge.
CONRAIL railroad tracks, used exclusively for freight traffic, run parallel to the back of the reactor site. Across the tracks, at a distance of about 25 m (80 ft.), is a storage warehouse that extends the length of the site. MIT Building NW13, which is presently used for nuclear engineering projects for nuclear chemistry studies,is about 46 m (150 ft.)
from the reactor building and is immediately adjacent to the side of the site away from Massachusetts Avenue. On the Massachusetts Avenue side of the site, about 25 m (80 ft.)
away from the reactor building, is an MIT-owned parking lot. At the front of the site, approximately 21 m (68 ft.) from the reactor building, is Albany Street. Although the site boundary comes nearest to the reactor on the side facing the railroad tracks, the closest point of normal public occupancy near the site boundary is on the Albany Stmet side.
Across Albany Street is a parking lot and facilities of a local commercial concern. Also across Albany Street but to the west of the reactor site is an MIT dormitory for graduate students. The area behind both the dormitory and the commercial concern is University Park which includes retail shopping and a hotel.
The site boundary of the MIT Research Reactor encompasses the restricted area (the area within the operations boundary), the reactor parking lot, and all of Building NW12.
(Nate: The parking lot is between the containment building and Albany Street. Parking is limited to authorized vehicles only.) The site boundary is approximately 21 m from the reactor building. The Emergency Planning Zone or EPZ is a 100 m radius surrounding the reactor containment building. This zone includes MIT-owned buildings, other privately held property, and public streets.
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LJ 3 Environmental Effects of MITR Ooeration -
3.1 ThermalImpact The fission energy generated in the MITR core is transferred to a closed primary coolant system, and to a secondary coolant system through the heat exchangers. The heat is then dissipated to the environment by means of a cooling tower. City water is used to replenish the secondary coolant loss mainly through evaporation. The rate of heat dissipation is comparable to that associated with local factories and other MIT Laboratories.
i Radiolocical Impact During Normal Ooeration 3.2 i
3.2.1 Environmental Monitoring Environmental monitoring is performed by using both continuous radiation
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Q monitors and dosimetry devices. The radiation monitoring system consists of GM detectors and associated electronics at remote locations with data transmitted continuously to the Reactor Radiation Protection Office and recorded. These remote sites are located 1
within a quarter mile radius of the facility. The detectable radiation levels are normally less 1 than 1.0 mrem per year, with an average of about 0.5 mrem (for 5000 kW operations).
With the proposed power upgrade to 6000 kW, the average dose should remain less than I f
I mrem per year. This figure is negligible compared to an average exposure of 300 mrem per year to the public from natural occurring sources, such as radon, and 60 mrem per year from diagnostic x-rays, medical treatments, and consumer products ,
m 3.2.2 Personnel Exposure Monitoring The MIT Reactor Radiation Protection Office provides services for tracking personnel exposure. Each person who may use or handle radioactive materials must
.,Y m J.E. Turner Atoms, Radiation. and Radiation Protection,2nd Edition, John Wiley & Sons Inc.,1995.
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register with this office and receive radiation safety training. Radiation exposures to reactor personnel are administratively controlled to meet ALARA (as low as reasonably achievable) criteria.
Experience from MrrR operations shows that all personnel exposures are well below the whole body dose limit of 5000 mrem per year, as specified in 10 CFR Pan 20.
3.2.3 Solid Wastes i
Solid wastes generated at the MITR are low level wastes such as ion-exchange resins, filters, and cleaning materials. Solid wastes are stored on site for decay, dewatered i 1
if appropriate, compacted, and then sent to an appropriate waste disposal facility. j
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3.2.4 Liauid Wastes 1 The possible sources of liquid wastes include liquid waste storage tanks, cooling tower blowdown, and varion rinks. Liquid radioactive wastes generated at the facility are discharged only to the sanitary sewer serving the facility. Discharge of radioactive liquid effluents is controlled by daily sampling (cooling tower water), analysis of batch samples (waste tanks before discharge), and on-line monitoring (secondary coolant and waste tanks during discharge). All of the liquid waste volumes and their activities are recorded. The total tritium release is about 0.1 Ci per year, or about 0.01 pCi/ liter. In calculating the tritium concentration, no credit is taken for larger quantities of non-radioactive waste water that are discharged to the sanitary sewer system from other parts of MIT campus. Total activity less tritium in the liquid effluents amounts to about 100 Ci per year, mostly Co-60 and Cs-137.
1 Release of MITR's radioactive effluents to the environment complies with the MITR-Ill Technical Specifications and the provisions of 10 CFR Part 20.
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i 3.2.5 Radioactive Gas Effluent Radioactive gas effluent is discharged from the 150-foot containment building exhaust stack to the environment. All nuclides are well below the regulatory effluent concentration (EC) limits after using the authorized dilution factor, with the exception of 4
Ar-41 at about 0.5 EC (1x10 pCi/ml). Ar-41 is a noble gas with a short half-life of 1.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. As shown in Section 3.2.1 of this report, the radiation dose that results from Ar-41 at nearby monitored locatione is less than 1 mrem per year.
All gascotis radioactivities are in accordance with the MITR-III Technical Specifications and 10 CFR Part 20.1302.
l 3.2.6 Spent Fuel and Tritiated Heavy Water Shipments Fuel for the operation of the MITR and the heavy water for the reflector are ;
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( provided by the U.S. Depanment of Energy (DOE). MIT and DOE have a contractual arrangement whereby DOE retains title to both the fuel and the heavy water. DOE is obligated to take the spent fuel and tritiated heavy water for storage or reprocessing. The MITR generates about six spent fuel elements per year. These are stored on-site before being retumed to DOE. Tritiated heavy water in the reflector system needs to be replaced -
with fresh heavy water once tritium concentration builds up to a level that would present a bio-hazard to maintenance personnel if a spill were to occur. Replacement is required about every 10-15 years depending on the power history of the reactor.
Spent fuel and tritiated heavy water shipments an: made in accordance with current DOE, NRC, and DOT requirements.
3.3 RadiologicalImnact During Abnormal Operation SAR Chapter 13 provides accident analysis for the MITR. There is only one
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l accident scenario that would lead to an off-site radiation release. Other accident scenarios, 5
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'l such as loss of primary coolant and loss of primary coolant flow, would not cause the V reactor core to be uncovered and therefore the integrity of the fuel elements would be
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maintained.
I The maximum hypothetical accident, or MHA, for the MITR is postulated to be a coolant flow blockage in the fuel element that contains the hottest fuel plate. It is conservatively assumed that five coolant channels am blocked and that the active portions all four associated fuel plates melt completely. The fission products therefore are released j to the primary coolant system. It is further assumed that the fission products are released from the primary coolant system to the containment building and then from the containment ;
1 building to the environment.
The estimated dose to the public at the site boundary (21 m) during the subsequent t
two-hour period would be 381 mrem for whole-body. This value is within the 10 CFR 'l limit of 500 mrem for the general public. ;
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4 Benefits of Facility Onerations The mission of the MITR is to support the educational and research programs of the Massachusetts Institute of Technology. A related objective is to support similar programs at other local-area universities and hospitals. The major experimental capabilities of the MITR include:
a) In-core loops that replicate the environment of pressurized or boiling water reactors. The objectives include the study of mechanisms for materials failures and methods for improving water chemistries.
b) Medical therapy facilities for the trestment of certain cancers such as metastic melanoma and glioblastoma multiforme using neutron capture therapy.
c) Beam tubes for the conduct of neutron scattering experiments.
d) Irradiation facilities for the conduct of neutron activation analysis C}
a and for the production of short-lived medical isotopes.
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1 The focus of the MITR's research program has, as would be expected, changed J
over the four decades during which the reactor has operated. However, continuing themes include: medical therapy (neutron capture therapy and radiation synovectomy), use of activation analysis to promote human health (nutrition studies and quantification of air pollutants), and medical research (chemical control of brain function and osmium-iridium l
1 generators for diagnosis). l i
Upgrade of the MITR to 6000 kW will improve its experimental capabilities by producing higher neutron fluxes which lead to shorter irradiation times, higher concentrations of short-lived medical isotopes, and improved capability to conduct human therapy using neutron beams.
The MITR is also used for education at MIT. Three examples are illustrated as follows:
n a) Major projects provide thesis research at the B.S., M.S., and Q Ph.D. level for students. Many students prefer reactor-based projects because it provides them with an opportunity to utilize and synthesize the theoretical material that they have teamed in relevant experimental tests. i i
b) MITR supports laboratory courses with exercises such as time- )
of-flight neutron spectmm measurements, suberitical multiplication and spectra unfolding.
c) A small number (three or four per year) of highly motivated students are chosen for employment at the reactor. These students spend four months in an intensive training program and ;
i then take a two day exam administered by the NRC for a reactor operator's license. A year later they are eligible to obtain a senior operator's license and may panicipate in a second training cycle for that purpose.
I The MITR also serves as a regional educational facility. Tours are available to high school students, a lectum series on the applications of neutrons is offered to local-area science teachers, and visiting universities utilize the facility for both research and laboratory exercises.
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5 . Conclusions 5,1 ~ Non-radiolonical L
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Them is no non-radiological impact from either continued operation of the MITR at 7 ., -
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5000 kW or from increasing the MITR' power from 5000 kW to 6000 kW. ,
5.2 Radiolonical
-i During routine operation, - radiation exposums to mactor personnel are
- administratively controlled to meet the ALARA criteria. Routine exposure to the general public is estimated to be less than 1 mmm per year. These figures are well below the 10 CFR 20 limits of 5000 mrem per year for radiation workers and 500 mrem per year for the general public. Accidents other than the MHA would not result in a radioactive release to the environment or to the public because none would result in fuel damage. The MHA itselfis unlikely. If it were to occur, radioactive exposures to the public would be below the 10 CFR 20 limits. 4 i
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